Myxoedema Coma

History

Fact

Explanation

Previous hypothyroidism.

The myxoedema coma or hypothyroid coma is a rare but life threatening complication of hypothyroidism. [1] It is the most severe presentation of profound hypothyroidism and is often fatal in spite of therapy. [2] Some patients may have been treated for hypothyroidism but the crisis has been precipitated by a stress factor (as follows) [2] or some of them may have been ignoring the treatments. Still, some patients present with a crisis for the first time. [3] [4]

A precipitating factor

In patients with hypothyroidism, a stress factor can precipitate a myxoedema coma. The known stress factors are infections, burns, hypoglycemia, hypothermia, surgery, trauma and some drugs like Lithium. [1] [2] Treatment defaulters have been reported to present with more severe illness. [5] [6]

A varying degree of altered consciousness

The patients with hypothyroid coma can present with any degree of clouded consciousness ranging from mild to a severe psychotic state. [7] [8] Long-standing altered consciousness could be due to untreated hypothyroidism. [6] Some cases may represent stroke syndromes. [9] It's called "myxoedema madness" [10] But the other more common causes of altered consciousness should be evaluated and excluded. i.e. hepatic encephalopathy. [11]

Swelling of ankles

Edema of ankles or generalized edema is a common presentation severe hypothyroidism. [1] [10] [12] Laryngeal edema is a potential mortality factor. [13]

Generalized weakness

Muscle weakness and fatigue are very common features of hypothyroidism. [9] [14] It can affect various muscle groups. i.e. the diaphragm. [1]

Acute constipation

Due to the paralytic ileus in acute severe hypothyroidism. [15] [16] [17] Thyroxine is an essential hormone to maintain the bowel movements. [18]

Fainting

They can present with acute myocardial fibrillations, causing syncope. [19]

Sudden death

Sudden death has been reported in profound hypothyroidism. [20] The thermoregulation, cardiac dysfunction may be causative factors.

Examination

Fact

Explanation

Hypothermia

Thyroxine is important in thermoregulation mechanisms. [1] In hypothyroidism, the temperature set point is lowered. [2] Hypothermia is a common feature in severe hypothyroidism. [3] [4] [5] [6] [7] [8]

Skin changes

In addition to features of autoimmune diseases like vitiligo [9] [10], chronic dermatosis has been found in higher incidences in thyroid disorders. [9] Myxedema refers to the skin condition caused by increased glycosaminoglycan deposition in the skin. Generalized myxedema is still the classic cutaneous sign of hypothyroidism. The most notable content of these edematous parts are hyaluronic acid. [11] Apart from those, coarse skin, thick skin, yellow coloration, dry skin and reduced sweating have been reported commonly. [11] [12]

Peripheral edema

The edema is due to mucopolysaccharide deposition, as mentioned above. As a result the skin does not pit with pressure. [11]

Low blood pressure

Hypotension is one of the common symptoms of hypothyroidism. [13] [14] It's also a factor determining the mortality in hypothyroid coma. [15] Postural drop of blood pressure has also been reported in hypothyroid patients. [16]

A neck lump

A neck lump confirming a goiter is suggestive of a thyroid disorder. [17] [18] [19]

Features of autoimmune conditions

In instances where hypothyroidism is due to autoimmune thyroiditis. [20] [21] [22] The common findings are vitiligo[23], alopecia and rheumatoid features. [24] [25] [26]

In profound hypothyroidism, there is a fluid transudation in body cavities. [8] [27] [28] To exclude that, examining for dullness in chest and abdomen is necessary.

Altered consciuosness

Glasgow coma scale, Mini-Mental score and Mental State Examination are important, given there is adequate time. Patients can have a varying altered consciousness that probably might even progress to acute psychotic state, also known as "myxoedema madness" [29] [30] [31]

Differential Diagnoses

Fact

Explanation

Acute cardiac failure

The acute cardiac failure syndromes are defined as new-onset, gradual, or rapidly worsening HF signs and symptoms that require urgent therapy [1] which makes it an emergency just like myxedema coma and prompt differentiation should be done as to manage either condition. Some patients might present with a history of congestive cardiac failure [2] and in these cases, one should be very careful because it's easier to jump into a wrong conclusion. Cardiac failure usually presents with symptoms of congestion (exertional dyspnea and/or dyspnea at rest,
orthopnea, paroxyamal nocturnal dyspnea) and hypoperfusion (chest pain, palpitations). [3] [4] [5] [6] [7]

Hepatic encephalopathy

Same risk factors ( as in History segment) can precipitate hepatic encephalopathy. [8] It's important to assess whether there has been a history of liver diseases. Some features are common in both conditions. i.e. ascites, lack of consciousness. [9] [10]

Septic shock

Infection can precipitate both a hypothyroid crisis and a septic shock. The clinical features may be very similar and different to identify in emergency setting. [11] [12] [13] [14] Blood investigations for septicemia and thyroid function are keys for diagnosing.

Management - General Measures

Fact

Explanation

Maintaining the airway and securing the breathing

It's the utmost priority since the patients either may present with respiratory failure or progress into it. [1] [2] [3] [4] Artificial airway management i.e. intubation may be essential in some cases but may be difficult. [2]

Fluid management

A difficult decision, fluid supplementation is necessary in hypotension, and fluid restriction is necessary in hyponatremia. [1] [5] Fluid management should depend on the severity of each complication. In patients who have hyponatremia should be given hypertonic saline (i.e. 3%) and when hypotension is more prominet, 5%dextrose should be given. [1]

Warming

Managing the hypothermia by external warming, but the accompanying vasodilatation may precipitate hypotension. [1] Active re-warming can be life saving. [6] [7] [8]

The patient should be de-briefed about the crisis he/she had to undergo, and how to be adherent to the medication to avoid future episodes. The drug interactions, how to look for drug adverse effects also should be added, with how to store medicine, when and how to take them and when to get the next thyroid profile done. [12] [13] [14]

KYRIACOS UNA, JELSMA JENNIFER, JAMES MICHAEL, JORDAN SUE, SALLUH JORGE I. F.. Monitoring Vital Signs: Development of a Modified Early Warning Scoring (Mews) System for General Wards in a Developing Country. PLoS ONE [online] 2014 January [viewed 09 June 2014] Available from: doi:10.1371/journal.pone.0087073

Management - Specific Treatments

Fact

Explanation

Thyroid hormone supplementation

T3 (triiodothyronine) is the active hormone in the body. [1] Since in severe illnesses there can be a reduced conversion of T4 to T3, it's not very effective to give T4 (thyroxine) as the treatment option in emergency setting. [1] [2] T3 when given in intraveous form has a shorter half-life, so needs to give in loading dose followed by regular infusions. [3] Triiodothyronine may not be widely available in the ER setting, and also because of it's potent action can increase the incidence of myocardial infarction or heart failure thus mortality. Some reports show adequate recovery with oral T3. Intravenous T4 is also recognized as a form of management. Once the patient is stabilized, conversion to oral T4 can be achieved. [1] [2] [4] [5] [6] [7]

Intravenous steroids

Hypoadrenalism can be masked by hypothyroidism in a crisis. When thyroid hormones are replaced, hypoadrenalism becomes obvious. In emergency settings, to prevent associated mortality, intravenous setroids, preferably hydrocortisone is given. [1] [4] [5]

Maintenance with oral thyroxine

Daily thyroxine supplementation with oral tablets. The dose is to be stated small and gradually increased according to the TSH response as checked monthly. Once TSH reaches the desired level, yearly follow-up with thyroid profile is desirable. [8] [9] [10] [11]